1. Field of the Invention
The invention relates to a wireless communication device such as a wireless tag reader or noncontact IC card reader which communicates with a wireless communication medium such as a wireless tag or noncontact IC card by using an electromagnetic wave. For example, the invention relates to a wireless communication device applied to a medium processing apparatus which continuously processes wireless communication media such as securities, mail, and pass tickets at high speed. The invention also relates to a medium processing apparatus to which the wireless communication device is applied to sort and check wireless communication media.
2. Description of the Related Art
Jpn. Pat. Appln. KOKAI Publication No. 2003-296786 discloses an example of a wireless communication device which processes a wireless communication medium conveyed through a conveying path. Jpn. Pat. Appin. KOKAI Publication Nos. 2000-105800 and 2002-216092 disclose a technique in which a medium processing apparatus to which a wireless communication device is applied reads data and the like from a wireless communication medium to process it.
However, when continuously processing wireless communication media at high speed, e.g., when starting transmission of a command to the second wireless communication medium which enters the communication area of a wireless communication device while transmitting a command to the first wireless communication medium which has entered the communication area of the wireless communication device, these two signals (commands) interfere with each other, thereby disabling normal transmission to the first and second wireless communication media. As a result, the wireless communication media continuously conveyed at high speed cannot be appropriately processed, thus posing a problem.